Note that when converting an image file to hexadecimal (for example for storage in a source file to be sent out on a web page), no knowledge is needed about the BMP file. It's enough to just prcess the individual bytes in the file and convert to hex data to store in a C array.

There are a number of such conversion programs available, and they work just as well with *.exe files, *.bat, *.jpeg, *.bin, *.tar.gz, ...